Investigation of a new catalytic reaction of complex formation of cobalt (III) with nitroso-R-salt for the determination of microquantities of phosphate-ions

The catalytic action of phosphate-ions on the reaction of complex formation of cobalt (III) with nitroso-R-salt in a weakly acid medium has been found. The dependence of the rate of the catalytic reaction on temperature, concentrations of reagents and catalyst, pH of the medium, as well as on the presence of some anion and non-ion surface-active substances and accompanying inorganic minerals was studied. The optimum conditions for the determination of 0.1 mu g/ml PO43- in water were determined. A technique for the determination of phosphate-ion impurity up to 9x10(-5) % in the high-purity sodium iodide and 2x10(-4)% cesium iodide used for the single crystals growth is suggested.